Made the TS implementation for hashmap and hashset generic over all hashers

[VictorKoenders]

By default the hasher is RandomState but developers can override this. This PR makes ts-rs usable with e.g. https://docs.rs/rustc-hash/latest/rustc_hash/.

[VictorKoenders]

Added tests for HashMap, HashSet and examples on how to use custom hashers.

It seems like you can't use HashMap<K, V, CustomHasher> directly because the TS derive requires that all type arguments extend from TS. However with a type alias it works perfectly fine.

[escritorio-gustavo]

LGTM. I edited your tests to expect types instead of interfaces due to #203

[NyxCode]

Great! Don't see any problems, here, so let's get this merged. Thanks @VictorKoenders for the PR, and thanks @escritorio-gustavo for taking a look!